#118 Postby cyclogenesis » Tue Jun 28, 2011 12:29 pm
June 28, 2011
this Tuesday
12:00 Noon
Data that I've been collecting from various microwave sensors this morning, together with an improvement in the structured cloud pattern of satellite imagery early this Tuesday morning is indicating to me that an overall better organizational trend to this disturbed weather over the Bay of Campeche has begun. The cloud pattern has become somewhat more circular in appearance.
Now first, a look at your Dvorak Satellite intensity estimates from 1215Z earlier this Tuesday morning, June 28, shows that the disturbed weather has made it on the map with its first T-number of a 1.0, on the chart. This is notch #1, the bottom-level ranking, on the scale. This correlates with an estimated mean wind speed of 25 kts / 29 mph, at 715 AM this morning.
Further to this, microwave sounding data, also from earlier this Tuesday morning June 28, showed an estimated maximum wind speed of 28 kts, ALTHOUGH these winds were far-removed from the center, to the North-Northeast of the center. An ASCAT pass from last night, (which was the last one available), also confirmed the higher belt of winds near the surface (~25 kts) to be bounded between 22° North to 26° North latitudes, with only lighter winds near the center of the surface low pressure area, indicated much further South in your Bay of Campeche. That was from late last night.
Since then, cyclogenesis here, has been checking on surface weather observations for you. Although I don't speak-up often enough, but while I'm on the subject here, yesterday evening your Carnival Triumph cruise ship reported an East wind of 33 kts, and 2 nights ago, your Carnival Escstasy cruise ship reported a wind of 30 kts, so I was able to duplicate the validity of these observations, at the surface. (Why not report current ships right now??) Because there aren't any ship reports, anywhere close in the area, to give right now, that's why.
In looking at buoy #42055, aka, your Bay of Campeche buoy, there's been a 24-hour pressure change of -0.05" or from 1010.5 mb, down to 1008.8 mb; NOT really impressive, but is showing that pressures have fallen over the past 24-hours. As you'd expect, the wind speeds there have also begun INCREASING earlier this morning, whereby I've observed sustained winds up to 23 kts sustained, with a PEAK wind gust to 27 kts from the East. Water temperatures are holding around 84°. ...And your significant wave heights have INCREASED to 11 ft out there at that buoy late this morning.
While all these observations from buoys, ship, and satellite are interesting, what remains is the $64,000 question which is this--->> Is there a verifiable, distinct & CONSISTENT, (not transient), rotary circulation developed at the surface yet?? There's never a dense enough network of buoys & ship reports to confirm, and with the loss of QuikScat & ASCAT passes come once in a blue moon, it really requires the need for an Air Force Reserve Unit Recon. aircraft to investigate today. I don't think this should wait, given the improving satellite imagery appearances today.
Now, I am using some other experimental techniques for which one of them indicates a weak circulation having already started this morning, but with only a 5 - 15 kt radius of winds near the immediate center. Farther out, some 191 statute miles North-Northeast of the low pressure-centered area miles away, was purportedly where the maximum 25 - 30 kt winds were located, from an experimental 12Z analysis (7 AM CDT) this Tuesday morning. Last night's ASCAT was also able to verify a similar location & wind, as well.
Shear. Current shear late this morning is shown to be Westerly about 18 - 20 kts using a blend between satellite shear & model-analyzed shear, this Tuesday morning, June 28th, from a Westerly direction.
About the forecast shear.... The GFS is the most generous out of the 4 models I reviewed in creating a most favorable, reduced-shear environment over the next day or two. The other 3 models I reviewed, including your statistical-dynamical one, maintains about 14 - 20 kts of shearing (from the West), for the next 24-hours, between Tuesday morning, and early Wednesday morning. After Wednesday morning, forecast shear will really come way down, below 10 kts, and more deepening (intensifying) can occur then, at which case it'll probably at least graduate to minimal tropical storm strength, before crossing the coast Wednesday night.
It is appearing from satellite-derived upper winds late this Tuesday morning, that an upper-air high (anti-cyclone), is beginning to get established over the Southwest Gulf of Mexico. If so, then the GFS may be the only correct solution in reduced levels of wind shear. A tropical cyclone can still develop in the face of 15 kts of shear, but the rate of deepening (intensification), will be slower. Upper divergence has been status quo over the past 6 hours though, and have not really increased yet, either. On the last calculation, RI is only showing a 15% chance, low as I'd expect it to be for ONLY an area of disturbed weather.
I see a continuation of plenty of moisture supply forecast amongst the Southwestern Gulf area during the next 2 days with both GFS & EMX indicating mean RH levels 850 - 700 in excess of 70% RH. PW sounding data this morning shows widespread PW's exceeding 2.10" in the SW Gulf.
It does appear on high-definition, visible satellite imagery late this morning, that a broader, loose & somewhat elongated circulation is developing just North of 20.0° North, 93.5° West, at 11 AM, Tuesday morning, June 28, and stretched a bit Southwestward from there, using visible observations from the TCU field, in the visible channel. Anvil blow-off isn't showing quite as severe the shear there was present yesterday on Monday, however.
Because of last night's ASCAT & this morning's new experimental techniques I'm using, I question, though whether the winds near this broad, elongated loose center of circulation are that strong though. I think not; ||| Not just yet. However, it is ENCOURAGING to see showers developing closer to the center of the low pressure area, just to the East of it, and now new activity in the NW quadrant. This is one of the necessary & critical criteria for a tropical cyclone to DEEPEN (strengthen), is having showers organize & SUSTAIN themselves, for prolonged time periods, in the proximity of the center. So, this is a start. We'll see if they are persistent, which is critical.
In truth, the statistical-dynamical models forecast an increase to a tropical depression / borderline minimal tropical storm status in the next 36 hours, somewhere's close-up to 38 mph. Interestingly, the EMX 850 mb wind forecast, when reduced from that level to the surface, using a reduction ratio, yielded very similar output as well, about a full day ago.
Bottom line is this--->> If this were me making the call, I think the aircraft should be released this afternoon to investigate, given the improved satellite signature in its overall cloud pattern, and because of what visible imagery, microwave sounding data, and the fact that recent shower development is currently taking place near the low's center late this morning. Further to this, it's already been classified on the Dvorak scale with its first output reading at 1.0, finally graduating on to the scale. Waiting another day, I think, would be bad politics for Mexico, considering this is forecast to move ashore by Wednesday night, and wouldn't give them enough time to ready themselves, having to play catch-up, because of another tardy warning delay waiting upon aircraft to confirm. Even if it's not up-to-par yet, they can at least gather some important wind & pressure data, along with areal extent of winds.
For the record your NHC described the following low pressure area from this Tuesday morning, at 7 AM CDT.
Center estimated near
19.8° North
92.7° West -->> at 7 AM
Estimated movement off to the West-Northwest at 6 MPH (285°)
Estimated wind at 7 AM, 25 kts (29 mph).
Estimated minimum pressure 1006 mb / 29.71"
-- cyclogenesis
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I dont think this is Arlene...just not getting the feeling from it. It could be like TD2 last year though.
sorry
